Cards of this type are increasingly used as information carriers or data carriers for passports, check cashing cards, credit cards, drivers licenses, identification cards, pass cards and similar means of identification which must be protected both against complete forgeries by means of imitated cards and against falsifications by partial alteration of the data relating to the holder.
Known identity cards are manufactured in the form of a fused laminate in which a card core carrying the information is protected by transparent films differing in nature from the card core. German Offenlegungsschrift No. 2,308,876 describes an identity card consisting of a relatively thick carrier film and a thin transparent film, between which there is a special paper having internal features, such as watermarks, banknote print or the like, which serve as protection against forgeries and cause differences in the thickness of the paper. The three layers are laminated together in such a way that the internal features are manually, mechanically and/or visually detectable through the transparent film. Further markings which serve to identity the cardholder are provided at a suitable point in this known identity card. For example, a photograph in the form of a film transparency is inserted during lamination between the special paper and the carrier film and is firmly bonded to the special paper. Furthermore, it is possible, at any desired point on the front or rear of the identity card, to laminate onto the outside of the plastic material a strip of special paper printed according to security technology as a field for later signatures or other handwritten entries.
German Auslegeschrift No. 2,163,943 discloses a personal identity card comprising a combination of a support layer, an electrically conductive layer, a barrier layer, a photoconductive layer with an organic photoconductor, an optional covering layer, a protective layer on the photoconductive layer or the covering layer, a protective layer on the rear of the support layer, and an optional covering layer on the last-mentioned protective layer. In this personal identity card, a number of different materials are assembled to give a laminate which, due to the lack of homogeneity of the individual layers, can be split up so that it is possible to carry out forgeries. The manufacture of this personal identity card is carried out in such a way that the requisite data are printed with the aid of an offset-printing machine onto the inside of a transport, non-plastic polyvinyl chloride film. Over this, a layer of printing ink is printed which has a high hiding power and leaves only those areas free, which are envisaged for the signature and the photograph. A photoconductive layer with the organic photoconductor is charged to a voltage of -6 kV in a darkroom with the aid of a corona discharge and is introduced into a camera in which a lens system for taking a photograph of the cardholder and a lighting device are combined with a lens system for taking a photograph of signs with the aid of the lighting device. After the image-forming exposure, the electrostatic images are developed using a liquid developer, are dried and are bonded, without a fixing step, with the aid of a hot press onto the photoconductive layer of the previously prepared surface-protective layer consisting of the polyvinyl chloride film. A transparent, non-plastic polyvinyl chloride film which can contain requisite data on its inside is then pressed onto the rear. A white covering layer which covers an aluminum foil used as the conductive layer is then pressed onto the entire surface area. The white covering layer can also be pressed directly onto the rear of the photoconductive layer containing the organic photoconductor, or a milkywhite plate can be used as the base plate of the light-sensitive element.
It has also been proposed in the past that both the card cores and the protective films for the film laminates be made of thermoplastic, fusible polyvinyl chloride polymers. Multi-ply film laminates of polyvinyl chloride which are pressed at temperatures of 140.degree. C. under high pressures of about 15 bars (kg/cm.sup.2) withstand attempts at splitting to a considerable degree and thus make unauthorized alterations of exposed card data more difficult.